﻿using System;
using System.Collections;
using System.Linq;
using System.Text;
using System.Xml.Linq;

namespace DBXml
{
    /// <summary>
    /// Exemple by http://www.dotnetperls.com/alphanumeric-sorting
    /// Modified to accept XElement
    /// </summary>
    public class AlphanumComparatorFast : IComparer
    {
        private Constants.TipoOrdenacao tipoOrdenacao = Constants.TipoOrdenacao.Nome;

        public AlphanumComparatorFast()
        {
            tipoOrdenacao = Constants.TipoOrdenacao.Nome;
        }

        public AlphanumComparatorFast(Constants.TipoOrdenacao tipoOrdenacao)
        {
            this.tipoOrdenacao = tipoOrdenacao;
        }

        public int Compare(object x, object y)
        {
            XElement x1 = x as XElement;
            string s1;
            if (x1 == null)
            {
                s1 = x as string;
                if (s1 == null)
                {
                    return 0;
                }
            }
            else
            {
                s1 = x1.Attribute("nome").Value;
                if (tipoOrdenacao == Constants.TipoOrdenacao.Numero)
                {
                    s1 = x1.Attribute("numero").Value;
                }
            }
            XElement x2 = y as XElement;
            string s2;
            if (x2 == null)
            {
                s2 = y as string;
                if (s2 == null)
                {
                    return 0;
                }
            }
            else
            {
                s2 = x2.Attribute("nome").Value;
                if (tipoOrdenacao == Constants.TipoOrdenacao.Numero)
                {
                    s2 = x2.Attribute("numero").Value;
                }
            }

            int len1 = s1.Length;
            int len2 = s2.Length;
            int marker1 = 0;
            int marker2 = 0;

            while (marker1 < len1 && marker2 < len2)
            {
                char ch1 = s1[marker1];
                char ch2 = s2[marker2];

                char[] space1 = new char[len1];
                int loc1 = 0;
                char[] space2 = new char[len2];
                int loc2 = 0;

                do
                {
                    space1[loc1++] = ch1;
                    marker1++;

                    if (marker1 < len1)
                    {
                        ch1 = s1[marker1];
                    }
                    else
                    {
                        break;
                    }
                } while (char.IsDigit(ch1) == char.IsDigit(space1[0]));

                do
                {
                    space2[loc2++] = ch2;
                    marker2++;

                    if (marker2 < len2)
                    {
                        ch2 = s2[marker2];
                    }
                    else
                    {
                        break;
                    }
                } while (char.IsDigit(ch2) == char.IsDigit(space2[0]));

                string str1 = new string(space1);
                string str2 = new string(space2);

                int result;
                if (char.IsDigit(space1[0]) && char.IsDigit(space2[0]))
                {
                    int thisNumericChunk = int.Parse(str1);
                    int thatNumericChunk = int.Parse(str2);
                    result = thisNumericChunk.CompareTo(thatNumericChunk);
                }
                else
                {
                    result = str1.CompareTo(str2);
                }

                if (result != 0)
                {
                    return result;
                }
            }

            return len1 - len2;
        }
    }
}
